Odometer reading

MrHarris · 04-24-2009, 07:21 AM

Anyone know if changing the tires to a larger or smaller diameter affects the rate of the odometer? If so, is there a way to re-calibrate it to make it work with a new size tire?

MrHarris · 04-24-2009, 04:44 PM

bump, anyone know?

gr8000 · 04-24-2009, 05:45 PM

My logic says that odo reading will be different if the diameter is different (as compared to the exact stock diameter) but I don't know i there is a way to recalibrate the odo based on a different diameter.

lincoln · 04-24-2009, 09:52 PM

There are companies that do that... and it's something I'd recommend so your ABS, etc. isn't all out of whack.

GT3 Tim · 04-25-2009, 12:21 AM

Compared to stock tire diameter.....

Larger diameter will cause the speedometer to read LOWER than actual.

Small diameter will cause the speedometer to read HIGHER than actual.

Thus, with a larger diameter tire, your odo will record less mileage than actual

How you can easily figure out what the "error" is to figure the stock diameter and then figure the new tire diameter. Find the % difference and then apply that to your speedometer reading. For example, on my truck, I went up in diameter. Using the sizes available online for stock and new tires, I was able to figure about a 10% increae in diameter. So, when my speedo reads 64, I am doing about 70 (70.4mph). Make sense?

I am not sure how the M3 picks up the signal for speed (and thus the odo), but in my truck is in the tranny. So, if you were to re-gear the diff, you would have to calculate for that too. I ended up re-gearing my truck and "underdrove" it about 20%. So now, when I read 77, I am only doing 70.

Bimmer Nerd · 04-25-2009, 01:05 AM

yea it does affect the reading and the post above this explains it clearly !

+1 good explanation .

FStop7 · 04-25-2009, 01:31 AM

The odometer will read incorrectly if the speedometer reads incorrectly.

lkstaack · 04-29-2009, 11:02 AM

Changing the wheel diameter will affect your speedo reading but should not affect your ABS. However, your speedo is probably not spot on anyway. I believe that the factory is allowed up to 7% error. A speedo that is off will mean the odometer is off as well (as well as gas milage measured from distance).

Check your true speed with a GPS. I have checked many of my personal cars and found that they all read faster than actual speed. I once changed my wheel size to one that corrected my speedo error.

Ken37.73 · 04-29-2009, 12:49 PM

1) This is a calculator for what you're up to:
http://www.miata.net/garage/tirecalc.html

2) Remember this only relevant on the front tyres.

Draper · 03-28-2011, 02:54 PM

Quote:

Originally Posted by Ken37.73

1) This is a calculator for what you're up to:
http://www.miata.net/garage/tirecalc.html

2) Remember this only relevant on the front tyres.

Sorry to revive this thread from the dead...

Are you saying the speed is measured from the front wheels?

04-24-2009, 07:21 AM	#1
MrHarris yodog 197 Rep 5,025 Posts Drives: '86 Corolla Join Date: Jun 2007 Location: Diamond Bar, Ca iTrader: (5) Garage List 2009 BMW [10.00]	Odometer reading Anyone know if changing the tires to a larger or smaller diameter affects the rate of the odometer? If so, is there a way to re-calibrate it to make it work with a new size tire? __________________ 2009 E92 M3 \| Alpine White \| Black Extended \| Advan RS \| Turner Test Pipes \| Dinan Axle-Back \| OETuning \| Eibach Springs \| UUC SSK \| VRS Front Lip \| VRS Type I Diffuser \| Matte Black \| RPi Scoops \| MS Filter \| Yokohama AD08 \| F1 Pinnacle Special Thanks: Gintani \| OETuning \| eAs
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04-24-2009, 04:44 PM	#2
MrHarris yodog 197 Rep 5,025 Posts Drives: '86 Corolla Join Date: Jun 2007 Location: Diamond Bar, Ca iTrader: (5) Garage List 2009 BMW [10.00]	bump, anyone know? __________________ 2009 E92 M3 \| Alpine White \| Black Extended \| Advan RS \| Turner Test Pipes \| Dinan Axle-Back \| OETuning \| Eibach Springs \| UUC SSK \| VRS Front Lip \| VRS Type I Diffuser \| Matte Black \| RPi Scoops \| MS Filter \| Yokohama AD08 \| F1 Pinnacle Special Thanks: Gintani \| OETuning \| eAs
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04-24-2009, 05:45 PM	#3
gr8000 Major 72 Rep 1,171 Posts Drives: E92 M3 - DCT Join Date: Jul 2008 Location: Athens, Greece iTrader: (0)	My logic says that odo reading will be different if the diameter is different (as compared to the exact stock diameter) but I don't know i there is a way to recalibrate the odo based on a different diameter.
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04-24-2009, 09:52 PM	#4
lincoln Lieutenant 19 Rep 432 Posts Drives: 2009 Melbourne Red Coupe - DCT Join Date: Jan 2009 Location: Seattle (Puyallup) iTrader: (0)	There are companies that do that... and it's something I'd recommend so your ABS, etc. isn't all out of whack. __________________ 2009 Melbourne Red DCT \| Black Interior \| Carbon Fiber Trim \| Carbon Fiber Roof \| Cold Weather \| Premium \| Technology \| 19's \| Smartphone Integration \| iPod \|
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04-25-2009, 12:21 AM	#5
GT3 Tim Moderator 94 Rep 1,920 Posts Drives: 2014 MB E63S Join Date: Feb 2008 Location: Sacramento, CA iTrader: (0)	Compared to stock tire diameter..... Larger diameter will cause the speedometer to read LOWER than actual. Small diameter will cause the speedometer to read HIGHER than actual. Thus, with a larger diameter tire, your odo will record less mileage than actual How you can easily figure out what the "error" is to figure the stock diameter and then figure the new tire diameter. Find the % difference and then apply that to your speedometer reading. For example, on my truck, I went up in diameter. Using the sizes available online for stock and new tires, I was able to figure about a 10% increae in diameter. So, when my speedo reads 64, I am doing about 70 (70.4mph). Make sense? I am not sure how the M3 picks up the signal for speed (and thus the odo), but in my truck is in the tranny. So, if you were to re-gear the diff, you would have to calculate for that too. I ended up re-gearing my truck and "underdrove" it about 20%. So now, when I read 77, I am only doing 70. __________________ Tim <--- apparently likes "3" cars 2014 E63S -- The Rocket 2014 F30 328i -- Kids car 2008 E90 M3 -- Sold 2004 GT3 -- Sold 1997 M3/4 -- Sold 1995 M3 -- Sold
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04-25-2009, 01:05 AM	#6
Bimmer Nerd Major General 519 Rep 7,789 Posts Drives: 6MT F80 Join Date: Jun 2008 Location: Santa Monica, CA iTrader: (12)	yea it does affect the reading and the post above this explains it clearly ! +1 good explanation .
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04-25-2009, 01:31 AM	#7
FStop7 I like cars 329 Rep 5,052 Posts Drives: M6 Join Date: Oct 2008 Location: Newbury Park, CA iTrader: (3)	The odometer will read incorrectly if the speedometer reads incorrectly. __________________ My photostream: http://www.flickr.com/photos/racelap/
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04-29-2009, 11:02 AM	#8
lkstaack Second Lieutenant 130 Rep 247 Posts Drives: F30 335i Join Date: Mar 2009 Location: San Diego, CA iTrader: (0)	Changing the wheel diameter will affect your speedo reading but should not affect your ABS. However, your speedo is probably not spot on anyway. I believe that the factory is allowed up to 7% error. A speedo that is off will mean the odometer is off as well (as well as gas milage measured from distance). Check your true speed with a GPS. I have checked many of my personal cars and found that they all read faster than actual speed. I once changed my wheel size to one that corrected my speedo error.
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04-29-2009, 12:49 PM	#9
Ken37.73 Private 1st Class 23 Rep 473 Posts Drives: E92 M3 Jet Black Join Date: Jan 2008 Location: Ireland iTrader: (0)	1) This is a calculator for what you're up to: http://www.miata.net/garage/tirecalc.html 2) Remember this only relevant on the front tyres. __________________
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